| Summary: | 博士 === 國立中央大學 === 資訊工程研究所 === 97 === Web service technologies are best exploited by composing services, and BPEL (Web Services Business Process Execution Language) is adopted industrial-wide as the de facto service composition standard. However, a BPEL composite service is typically treated as a fully automated service flow that orchestrates multiple web services and involves no user interactions – a desirable feature for service delivery, and is presently not included in the BPEL standard. Open Service Gateway Initiative (OSGi) has been widely adopted in the deployment and execution of collaborative software components and the development of service-oriented pervasive computing applications in a variety of embedded devices. However, how to collaboratively communicate among the distributed OSGi service bundles is not considered in current OSGi specifications. In this work, we propose an extension to BPEL to infuse user interactions into composite services along three dimensions: (1) to develop two BPEL extension activities to describe the inner workings of user interactions in BPEL service and the rendering of service user interfaces; (2) to provide a wizard-style mechanism to guide the user to interact with the service flow in accordance with the sequence of service execution; and (3) to devise a UI service communication protocol to facilitate secure cross-domain communication among UI services from various domains. Thus, an enhanced BPEL engine with a service UI rendering engine has been accordingly developed. The work also proposes a BPEL-based decentralized OSGi service composition approach to integrating our previous work on agent service framework to facilitate decentralized OSGi service composition across the resource-limited embedded devices along three dimensions: (1) to cooperate with the agent services to access distributed OSGi services; (2) to provide an BPEL-based agent itinerary to guide the agent service where to migrate and what services are available for access on current site; and (3) to elucidate the design principles for the development of light-weight BPEL engine.
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